The proposed research investigates nocebo and placebo responses in relation to contagion via a bogus cold viral challenge paradigm. Positive effects of pharmacologically inert compounds, termed "placebo effects," have long been recognized. The inverse result, dubbed "nocebo," is when inert compounds evoke negative health consequences. There has been relatively little exploration thus far of how placebos/nocebos work in terms of mediating mechanisms or moderating factors. The proposed exploratory research will investigate whether "magical contagion beliefs" about the source of a cold virus can produce measurable effects on perceived symptoms, and mediators and moderators of those effects. In a modified version of the viral cold challenge paradigm, the proposed protocol applies psychological and physiological measures to assess participants' responses to exposure to biologically inert substances (saline nose drops) after they have been led to believe the substances are viral preparations from one of three sources: a morally neutral source (a virus pool), a positive interpersonal source, and a negative interpersonal source. The key question is whether participants will experience more (and/or more severe) perceived symptoms if the source was negative, and less (and/or less severe) perceived symptoms if the source was positive? Also of interest is whether a marker of nonspecific immunity, slgA, follows the same pattern as perceptions. It is important to note that both directions of effect are of interest - whether negative beliefs compromise perceived health and actual immune function (nocebo) as well as whether positive beliefs bolster perceived and actual resistance (placebo), relative to a neutral condition. Finally, the role of potential mediating factors such as mood, stress (as measured by cortisol), and specific magical contagion-related cognitions, and of potential moderating factors, such as background levels of psychological stress (daily hassles), health locus of control and rational-experiential response style, will be assessed as they influence susceptibility to placebo/nocebo effects. Repeated measures of perceived symptoms, mood, hassles, slgA, and cortisol, as well as open-ended and checklist tracking of specific cognitions and remedial behaviors, over a four day period, will allow assessment of how the various processes play out over time to produce effects. In sum, this research aims to identify cognitive factors that either promote or diminish disease perception and objective susceptibility, in context of a bogus viral challenge paradigm.